package day2;

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Test10 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int n = in.nextInt();
            while(n > 9) {
                n = sum(n);
            }
            System.out.println(n);
        }
    }

    public static int sum(int n) {
        int sum = 0;
        while(n > 9) {
            sum = sum + n % 10;
            n = n / 10;
        }
        sum += n;
        return sum;
    }
}
